APA (7th ed.) Citation

Guy, R. K. (2004). Unsolved Problems in Number Theory (Third edition.). Springer New York.

Chicago Style (17th ed.) Citation

Guy, Richard K. Unsolved Problems in Number Theory. Third edition. New York, NY: Springer New York, 2004.

MLA (9th ed.) Citation

Guy, Richard K. Unsolved Problems in Number Theory. Third edition. Springer New York, 2004.

Warning: These citations may not always be 100% accurate.